Hi Nathan, I did not mean that SQLAlchemy can do this out of the box ;)
Cheers, Angelos On Tue, Aug 6, 2013 at 12:52 PM, Nathan Woodrow <[email protected]> wrote: > SQLAlchemy is a ORM it's not going to help with any kind of caching. > > There are plans for creating a in memory feature cache of sorts so that we > don't have to fetch each feature everytime however there is a bit of > work involved in making sure we update the view when the data > source changes. > > - Nathan > > > On Tue, Aug 6, 2013 at 7:33 PM, Angelos Tzotsos <[email protected]>wrote: > >> Hi all, >> >> I am *guessing* that Manifold is using the .NET Dataset type to cache >> data, and that some kind of db manager takes care of the sync. >> >> SQLAlchemy could be used in a python plugin for the same purpose. >> >> Best, >> Angelos >> >> >> >> On Tue, Aug 6, 2013 at 9:46 AM, Marco Hugentobler < >> [email protected]> wrote: >> >>> Hi Willem >>> >>> Another thing to explore is the offline editing plugin. It caches >>> postgis layers to a local spatialite database and can even be used to >>> synchronise edits between local spatialite db and remote postgis db. >>> >>> >>> >Sourcepole have developed (for NIWA, New Zealand) a plugin that >>> supports local caching of WMS & WFS data sources. This could probably be >>> adapted to support other input >formats. Marco Hugentobler did the coding >>> for this - he can perhaps comment? >>> >>> The plugin saves WMS as local rasters and WFS as local vectors. This is >>> similar to save as local vector / raster file by hand. However the plugin >>> is more convenient because it manages the local storage and the reference >>> to the remote uri. It has some other nice features like synchronizing / >>> offlining in a graphical way. Btw., we hope to include this plugin (a C++ >>> one) into the main repository after 2.0 feature freeze is over. >>> >>> Regards, >>> Marco >>> >>> On 06.08.2013 03:20, Brent Wood wrote: >>> >>> Hi Willem, >>> >>> Why can you not save such a layer or a selection from such a layer, as >>> a local shapefile (or other supported format). is this not effectively a >>> "local cache"? Delete/overwrite when you desire. >>> >>> Where is the performance bottleneck? Postgis, network, QGIS? Just >>> creating a local cache will not necessarily speed things up, if your >>> database is on a fast server with a fast network, it may even get slower. >>> >>> Sourcepole have developed (for NIWA, New Zealand) a plugin that >>> supports local caching of WMS & WFS data sources. This could probably be >>> adapted to support other input formats. Marco Hugentobler did the coding >>> for this - he can perhaps comment? >>> >>> As Nathan says, caching a local snapshot of a dynamic, multi-user >>> database will result in something that gets out of sybc with the source >>> pretty quickly. Caching a local copy of a largely static database is >>> relatively safe. >>> >>> Cheers >>> >>> Brent >>> ------------------------------ >>> *From:* Nathan Woodrow <[email protected]> <[email protected]> >>> *To:* Willem Buitendyk <[email protected]> <[email protected]> >>> *Cc:* qgis-user <[email protected]> <[email protected]>; >>> "[email protected]" <[email protected]> >>> <[email protected]> <[email protected]> >>> *Sent:* Tuesday, August 6, 2013 11:07 AM >>> *Subject:* Re: [Qgis-user] Caching remote postgis layers? >>> >>> Hey Willem, >>> >>> I'm not aware of a feature like that. The best place to ask this >>> question to see if anyone is working, or planning to work, on it is the >>> developer list. I have copied it in so it show up there too. >>> >>> Caching could be done by storing the returned results in a memory >>> spatialite database. The tricky thing is knowing when to get any new >>> results from the postgis database when things have changed on the database. >>> How does Manifold handling viewing an area, updating something using SQL >>> on the database (not though Manifold) and then looking at that area again? >>> >>> - Nathan >>> >>> >>> On Tue, Aug 6, 2013 at 2:44 AM, Willem Buitendyk <[email protected]>wrote: >>> >>> I've noticed looking at the roadmap that caching remote postgis data is >>> not on the list. I love qgis but a lot of my work involves connecting to a >>> remote postgis database. The speed of navigating a large dataset is, at >>> the moment, rather unbearable. I also use Manifold GIS and the difference >>> in speed is shocking, presumably because Manifold is caching the dataset. >>> This seems like it should be a relatively easy thing to implement. Is >>> there interest on this board for this feature? I was thinking at taking a >>> stab at contributing to the source code but am wondering about methods to >>> achieve data caching most efficiently. Look forward to others thoughts? >>> Or maybe I missing something that is already in place? >>> >>> Willem >>> >>> _______________________________________________ >>> Qgis-user mailing list >>> [email protected] >>> http://lists.osgeo.org/mailman/listinfo/qgis-user >>> >>> >>> >>> _______________________________________________ >>> Qgis-user mailing list >>> [email protected] >>> http://lists.osgeo.org/mailman/listinfo/qgis-user >>> >>> >>> >>> >>> _______________________________________________ >>> Qgis-developer mailing >>> [email protected]http://lists.osgeo.org/mailman/listinfo/qgis-developer >>> >>> >>> >>> -- >>> Dr. Marco Hugentobler >>> Sourcepole - Linux & Open Source Solutions >>> Weberstrasse 5, CH-8004 Zürich, [email protected] >>> http://www.sourcepole.ch >>> Technical Advisor QGIS Project Steering Committee >>> >>> >>> _______________________________________________ >>> Qgis-developer mailing list >>> [email protected] >>> http://lists.osgeo.org/mailman/listinfo/qgis-developer >>> >>> >> >> >> -- >> Angelos Tzotsos >> Remote Sensing Laboratory >> National Technical University of Athens >> http://users.ntua.gr/tzotsos >> >> _______________________________________________ >> Qgis-developer mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-developer >> >> > -- Angelos Tzotsos Remote Sensing Laboratory National Technical University of Athens http://users.ntua.gr/tzotsos
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